Regular breast cancer screening reduces deaths substantially

No link between mammograms and thyroid cancer, local doctors say

WATERLOO REGION — The chances of surviving breast cancer are improved through regular screening, yet one out of three eligible women in the region are not getting mammograms.

Catching breast cancer early through mammograms allows earlier and more successful treatment.

“Breast cancer screening does save lives, so it’s very important,” Dr. Chad Lavallee, chief of radiology at St. Mary’s General Hospital.

Research shows regular screening of women age 50 to 69 can reduce deaths by 21 per cent.

Breast cancer is the most common cancer in women, affecting one in nine. An estimated 9,100 women will be diagnosed with breast cancer in Ontario this year and 2,000 will die from the disease.

October is breast cancer awareness month.

The Ontario Breast Screening Programrecommends women between 50 and 74 get a mammogram every two years. Those at higher risk who have a family history of breast cancer can start screening earlier with a mammogram, genetic testing and breast MRI.

“You’re picking it up usually when it’s smaller,” said Dr. Samantha Fienberg, a radiologist at Grand River Hospital. “Women who go through screening, the survival rate’s better.”

All Waterloo Region’s hospitals offer mammograms through the Ontario Breast Screening Program, which does not require a doctor’s referral. Women over 50 can call to make an appointment and reminders are sent after enrolling when it’s time for another mammogram.

Across Ontario, about two-thirds of women are screened regularly, Fienberg said. That is, however, a substantial increase from about six years ago when the rate was only one in four.

Mammograms are also done when a doctor wants to investigate a lump or other irregularity.

There have been reports in the media — in particular the Dr. Oz television show, and circulating on the internet — that link routine mammograms to thyroid cancer. That has prompted calls to use a thyroid shield or collar during the test to reduce radiation exposure to the small gland at the front of the neck.

However, local health care professionals stressed there is no evidence linking mammograms and thyroid cancer. The thyroid is not exposed to the direct X-ray beam and the scattered radiation is equal to 30 minutes of background radiation people get every day from the environment.

The National Cancer Institute in the United States reports the rate of thyroid cancer rose from 1998 to 2007, Fienberg said. However, she added, “the incidence of male and female thyroid cancer has been increasing at the same rate.”

The rise in cases is likely linked with better detection and more sensitive ultrasounds to find cancer in the small gland, she said.

“The amount of radiation going to the thyroid is minimal over a lifetime,” Fienberg said of screening mammograms.

The Canadian Cancer Society estimates 5,600 people will be diagnosed with thyroid cancer in Canada this year. That’s less than two-thirds of the number of women diagnosed with breast cancer in Ontario alone.

All local hospitals use digital mammogram units, which reduce radiation exposure by 25 per cent to 50 per cent compared to traditional units

“Already our radiation exposure is much less,” Lavallee said.

St. Mary’s has posted in its change rooms a 2011 notice from Cancer Care Ontario about the use of thyroid shields, which is reviewed by the technologist with the patient before the mammogram.

It states: “The use of thyroid shields is not indicated for mammography. The dose to the thyroid from mammography is negligible and there is no scientific reason to supply thyroid collars for this examination.”

“With most patients, they are quite fine with that explanation,” said Runnquist, adding that only a few women a year ask to use the shield while getting a mammogram.

A thyroid shield can actually require more images to be taken because it hampers views of the breast, possibly even causing suspect tissue that could be cancerous to be missed. Normally, two images are taken of each breast from the top and side.

The thyroid shield can obscure areas or cause a washed-out image because it’s so much darker than breast tissue.

“It really reduces the quality of the mammogram and may result in repeat takes of the mammogram,” Fienberg said.

“Using the thyroid shield is not really something we recommend.”

Find out more about the Ontario Breast Cancer Screening program at www.cancercare.on.caor call 1-800-668-9304.